Interoperability Test Case Descriptions
=======================================

Client and server use
[test.proto](https://github.com/grpc/grpc/blob/master/test/cpp/interop/test.proto)
and the [gRPC over HTTP/2 v2
protocol](https://github.com/grpc/grpc-common/blob/master/PROTOCOL-HTTP2.md).

Client
------

Clients implement test cases that test certain functionally. Each client is
provided the test case it is expected to run as a command-line parameter. Names
should be lowercase and without spaces.

Clients should accept these arguments:
* --server_host=HOSTNAME
    * The server host to connect to. For example, "localhost" or "127.0.0.1"
* --server_host_override=HOSTNAME
    * The server host to claim to be connecting to, for use in TLS and HTTP/2
      :authority header. If unspecified, the value of --server_host will be
      used
* --server_port=PORT
    * The server port to connect to. For example, "8080"
* --test_case=TESTCASE
    * The name of the test case to execute. For example, "empty_unary"
* --use_tls=BOOLEAN
    * Whether to use a plaintext or encrypted connection
* --use_test_ca=BOOLEAN
    * Whether to replace platform root CAs with
      [ca.pem](https://github.com/grpc/grpc/blob/master/src/core/tsi/test_creds/ca.pem)
      as the CA root

Clients must support TLS with ALPN. Clients must not disable certificate
checking.

### empty_unary

This test verifies that implementations support zero-size messages. Ideally,
client implementations would verify that the request and response were zero
bytes serialized, but this is generally prohibitive to perform, so is not
required.

Server features:
* [EmptyCall][]

Procedure:
 1. Client calls EmptyCall with the default Empty message

Asserts:
* call was successful
* response is non-null

*It may be possible to use UnaryCall instead of EmptyCall, but it is harder to
ensure that the proto serialized to zero bytes.*

### large_unary

This test verifies unary calls succeed in sending messages, and touches on flow
control (even if compression is enabled on the channel).

Server features:
* [UnaryCall][]
* [Compressable Payload][]

Procedure:
 1. Client calls UnaryCall with:

    ```
    {
      response_type: COMPRESSABLE
      response_size: 314159
      payload:{
        body: 271828 bytes of zeros
      }
    }
    ```

Asserts:
* call was successful
* response payload type is COMPRESSABLE
* response payload body is 314159 bytes in size
* clients are free to assert that the response payload body contents are zero
  and comparing the entire response message against a golden response

### client_streaming

This test verifies that client-only streaming succeeds.

Server features:
* [StreamingInputCall][]
* [Compressable Payload][]

Procedure:
 1. Client calls StreamingInputCall
 2. Client sends:

    ```
    {
      payload:{
        body: 27182 bytes of zeros
      }
    }
    ```
 3. Client then sends:

    ```
    {
      payload:{
        body: 8 bytes of zeros
      }
    }
    ```
 4. Client then sends:

    ```
    {
      payload:{
        body: 1828 bytes of zeros
      }
    }
    ```
 5. Client then sends:

    ```
    {
      payload:{
        body: 45904 bytes of zeros
      }
    }
    ```
 6. Client halfCloses

Asserts:
* call was successful
* response aggregated_payload_size is 74922

### server_streaming

This test verifies that server-only streaming succeeds.

Server features:
* [StreamingOutputCall][]
* [Compressable Payload][]

Procedure:
 1. Client calls StreamingOutputCall with:

    ```
    {
      response_type:COMPRESSABLE
      response_parameters:{
        size: 31415
      }
      response_parameters:{
        size: 9
      }
      response_parameters:{
        size: 2653
      }
      response_parameters:{
        size: 58979
      }
    }
    ```

Asserts:
* call was successful
* exactly four responses
* response payloads are COMPRESSABLE
* response payload bodies are sized (in order): 31415, 9, 2653, 58979
* clients are free to assert that the response payload body contents are zero
  and comparing the entire response messages against golden responses

### ping_pong

This test verifies that full duplex bidi is supported.

Server features:
* [FullDuplexCall][]
* [Compressable Payload][]

Procedure:
 1. Client calls FullDuplexCall with:

    ```
    {
      response_type: COMPRESSABLE
      response_parameters:{
        size: 31415
      }
      payload:{
        body: 27182 bytes of zeros
      }
    }
    ```
 2. After getting a reply, it sends:

    ```
    {
      response_type: COMPRESSABLE
      response_parameters:{
        size: 9
      }
      payload:{
        body: 8 bytes of zeros
      }
    }
    ```
 3. After getting a reply, it sends:

    ```
    {
      response_type: COMPRESSABLE
      response_parameters:{
        size: 2653
      }
      payload:{
        body: 1828 bytes of zeros
      }
    }
    ```
 4. After getting a reply, it sends:

    ```
    {
      response_type: COMPRESSABLE
      response_parameters:{
        size: 58979
      }
      payload:{
        body: 45904 bytes of zeros
      }
    }
    ```

Asserts:
* call was successful
* exactly four responses
* response payloads are COMPRESSABLE
* response payload bodies are sized (in order): 31415, 9, 2653, 58979
* clients are free to assert that the response payload body contents are zero
  and comparing the entire response messages against golden responses

### empty_stream

This test verifies that streams support having zero-messages in both
directions.

Server features:
* [FullDuplexCall][]

Procedure:
 1. Client calls FullDuplexCall and then half-closes

Asserts:
* call was successful
* exactly zero responses

### compute_engine_creds

Status: Not yet implementable

This test is only for cloud-to-prod path.

This test verifies unary calls succeed in sending messages while using Service
Credentials from GCE metadata server. The client instance needs to be created
with desired oauth scope.

Server features:
* [UnaryCall][]
* [Compressable Payload][]
* SimpeResponse.username
* SimpleResponse.oauth_scope

Procedure:
 1. Client sets flags default_service_account with GCE service account name and
    oauth_scope with the oauth scope to use.
 2. Client configures channel to use GCECredentials
 3. Client calls UnaryCall on the channel with:

    ```
    {
      response_type: COMPRESSABLE
      response_size: 314159
      payload:{
        body: 271828 bytes of zeros
      }
      fill_username: true
      fill_oauth_scope: true
    }
    ```

Asserts:
* call was successful
* received SimpleResponse.username equals FLAGS_default_service_account
* received SimpleResponse.oauth_scope is in FLAGS_oauth_scope
* response payload body is 314159 bytes in size
* clients are free to assert that the response payload body contents are zero
  and comparing the entire response message against a golden response

### service_account_creds

Status: Not yet implementable

This test is only for cloud-to-prod path.

This test verifies unary calls succeed in sending messages while using JWT
signing keys (redeemed for OAuth2 access tokens by the auth implementation)

Server features:
* [UnaryCall][]
* [Compressable Payload][]
* SimpleResponse.username
* SimpleResponse.oauth_scope

Procedure:
 1. Client sets flags service_account_key_file with the path to json key file,
    oauth_scope to the oauth scope.
 2. Client configures the channel to use ServiceAccountCredentials.
 3. Client calls UnaryCall with:

    ```
    {
      response_type: COMPRESSABLE
      response_size: 314159
      payload:{
        body: 271828 bytes of zeros
      }
      fill_username: true
      fill_oauth_scope: true
    }
    ```

Asserts:
* call was successful
* received SimpleResponse.username is in the json key file read from
  FLAGS_service_account_key_file
* received SimpleResponse.oauth_scope is in FLAGS_oauth_scope
* response payload body is 314159 bytes in size
* clients are free to assert that the response payload body contents are zero
  and comparing the entire response message against a golden response

### jwt_token_creds

Status: Not yet implementable

This test is only for cloud-to-prod path.

This test verifies unary calls succeed in sending messages while using JWT
token (created by the project's key file)

Server features:
* [UnaryCall][]
* [Compressable Payload][]
* SimpleResponse.username
* SimpleResponse.oauth_scope

Procedure:
 1. Client sets flags service_account_key_file with the path to json key file
 2. Client configures the channel to use JWTTokenCredentials.
 3. Client calls UnaryCall with:

    ```
    {
      response_type: COMPRESSABLE
      response_size: 314159
      payload:{
        body: 271828 bytes of zeros
      }
      fill_username: true
    }
    ```

Asserts:
* call was successful
* received SimpleResponse.username is in the json key file read from
  FLAGS_service_account_key_file
* response payload body is 314159 bytes in size
* clients are free to assert that the response payload body contents are zero
  and comparing the entire response message against a golden response

### Metadata (TODO: fix name)

Status: Not yet implementable

This test verifies that custom metadata in either binary or ascii format can be
sent in header and trailer.

Server features:
* [UnaryCall][]
* [Compressable Payload][]
* Ability to receive custom metadata from client in header and send custom data
  back to client in both header and trailer. (TODO: this is not defined)

Procedure:
 1. While sending custom metadata (ascii + binary) in the header, client calls UnaryCall with:

    ```
    {
      response_type: COMPRESSABLE
      response_size: 314159
      payload:{
        body: 271828 bytes of zeros
      }
    }
    ```

Asserts:
* call was successful
* custom metadata is echoed back in the response header.
* custom metadata is echoed back in the response trailer.

### status_code_and_message

Status: Not yet implementable

This test verifies unary calls succeed in sending messages, and propagates back
status code and message sent along with the messages.

Server features:
* [UnaryCall][]

Procedure:
 1. Client calls UnaryCall with:

    ```
    {
      response_status:{
        code: 2
        message: "test status message"
      }
    }
    ```

Asserts:
* received status code is the same with sent code
* received status message is the same with sent message

### unimplemented_method

Status: Not yet implementable

This test verifies calling unimplemented RPC method returns unimplemented
status.

Procedure:
* Client calls UnimplementedCall with:

    ```
    {
      response_type: COMPRESSABLE
      response_size: 314159
      payload:{
        body: 271828 bytes of zeros
      }
    }
    ```

Asserts:
* received status code is 12 (UNIMPLEMENTED)
* received status message is empty or null/unset

### cancel_after_begin

This test verifies that a request can be cancelled after metadata has been sent
but before payloads are sent.

Server features:
* [StreamingInputCall][]

Procedure:
 1. Client starts StreamingInputCall
 2. Client immediately cancels request

Asserts:
* Call completed with status CANCELLED

### cancel_after_first_response

This test verifies that a request can be cancelled after receiving a message
from the server.

Server features:
* [FullDuplexCall][]
* [Compressable Payload][]

Procedure:
 1. Client starts FullDuplexCall with

    ```
    {
      response_type: COMPRESSABLE
      response_parameters:{
        size: 31415
      }
      payload:{
        body: 27182 bytes of zeros
      }
    }
    ```
 2. After receiving a response, client cancels request

Asserts:
* Call completed with status CANCELLED

### concurrent_large_unary

Status: TODO

Client performs 1000 large_unary tests in parallel on the same channel.

### Flow control. Pushback at client for large messages (TODO: fix name)

Status: TODO

This test verifies that a client sending faster than a server can drain sees
pushback (i.e., attempts to send succeed only after appropriate delays).

### TODO Tests

High priority:

Propagation of status code and message (yangg)

Cancel after sent headers (ctiller - done)

Cancel after received first message (ctiller - done)

Timeout after expire (zhaoq)

Zero-message streams (ejona)

Multiple thousand simultaneous calls on same Channel (ctiller - done)

OAuth2 tokens + Service Credentials from GCE metadata server (GCE->prod only)
(abhishek)

OAuth2 tokens + JWT signing key (GCE->prod only) (abhishek)

Metadata: client headers, server headers + trailers, binary+ascii (chenw)

Normal priority:

Cancel before start (ctiller)

Cancel after sent first message (ctiller)

Cancel after received headers (ctiller)

Timeout but completed before expire (zhaoq)

Multiple thousand simultaneous calls timeout on same Channel (ctiller)

Lower priority:

Flow control. Pushback at client for large messages (abhishek)

Flow control. Pushback at server for large messages (abhishek)

Going over max concurrent streams doesn't fail (client controls itself)
(abhishek)

RPC method not implemented (yangg)

Multiple thousand simultaneous calls on different Channels (ctiller)

Failed TLS hostname verification (ejona?)

To priorize:

Start streaming RPC but don't send any requests, server responds

### Postponed Tests

Resilience to buggy servers: These tests would verify that a client application
isn't affected negatively by the responses put on the wire by a buggy server
(e.g. the client library won't make the application crash).

Reconnect after transport failure

Reconnect backoff

Fuzz testing


Server
------

Servers implement various named features for clients to test with. Server
features are orthogonal. If a server implements a feature, it is always
available for clients. Names are simple descriptions for developer
communication and tracking.

Servers should accept these arguments:

* --port=PORT

    * The port to listen on. For example, "8080"

* --use_tls=BOOLEAN

    * Whether to use a plaintext or encrypted connection

Servers must support TLS with ALPN. They should use
[server1.pem](https://github.com/grpc/grpc/blob/master/src/core/tsi/test_creds/server1.pem)
for their certificate.

### EmptyCall
[EmptyCall]: #emptycall

Server implements EmptyCall which immediately returns the empty message.

### UnaryCall
[UnaryCall]: #unarycall

Server implements UnaryCall which immediately returns a SimpleResponse with a
payload body of size SimpleRequest.response_size bytes and type as appropriate
for the SimpleRequest.response_type. If the server does not support the
response_type, then it should fail the RPC with INVALID_ARGUMENT.

If the request sets fill_username, the server should return the client username
it sees in field SimpleResponse.username. If the request sets fill_oauth_scope,
the server should return the oauth scope of the rpc in the form of "xapi_zoo"
in field SimpleResponse.oauth_scope.

### StreamingInputCall
[StreamingInputCall]: #streaminginputcall

Server implements StreamingInputCall which upon half close immediately returns
a StreamingInputCallResponse where aggregated_payload_size is the sum of all
request payload bodies received.

### StreamingOutputCall
[StreamingOutputCall]: #streamingoutputcall

Server implements StreamingOutputCall by replying, in order, with one
StreamingOutputCallResponses for each ResponseParameters in
StreamingOutputCallRequest. Each StreamingOutputCallResponses should have a
payload body of size ResponseParameters.size bytes, as specified by its
respective ResponseParameters. After sending all responses, it closes with OK.

### FullDuplexCall
[FullDuplexCall]: #fullduplexcall

Server implements FullDuplexCall by replying, in order, with one
StreamingOutputCallResponses for each ResponseParameters in each
StreamingOutputCallRequest. Each StreamingOutputCallResponses should have a
payload body of size ResponseParameters.size bytes, as specified by its
respective ResponseParameters. After receiving half close and sending all
responses, it closes with OK.

### Compressable Payload
[Compressable Payload]: #compressable-payload

When the client requests COMPRESSABLE payload, the response includes a payload
of the size requested containing all zeros and the payload type is
COMPRESSABLE.

### Observe ResponseParameters.interval_us
[Observe ResponseParameters.interval_us]: #observe-responseparametersinterval_us

In StreamingOutputCall and FullDuplexCall, server delays sending a
StreamingOutputCallResponse by the ResponseParameters's interval_us for that
particular response, relative to the last response sent. That is, interval_us
acts like a sleep *before* sending the response and accumulates from one
response to the next.

Interaction with flow control is unspecified.

### Echo Auth Information

Status: Pending

If a SimpleRequest has fill_username=true and that request was successfully
authenticated, then the SimpleResponse should have username filled with the
canonical form of the authenticated source. The canonical form is dependent on
the authentication method, but is likely to be a base 10 integer identifier or
an email address.

Discussion:

Ideally, this would be communicated via metadata and not in the
request/response, but we want to use this test in code paths that don't yet
fully communicate metadata.